Astrobiology

Natural History, Feb, 2000 by Robert (American businessperson and engineer) Anderson

Water has been found in the soils of the polar craters of the Moon. One of the missions of the failed Mars Polar Lander was to look for signs of frozen water in the soil of the red planet. Investigating the watery, methane-rich atmosphere of Saturn's moon Titan and the suspected liquid ocean beneath the icy surface of Jupiter's moon Europa is a major goal for future exploration. Water being one of the prerequisites for life, these efforts are part of a larger astrobiological NASA mission to probe the origin and distribution of life in the universe.

A rather broad discipline, astrobiology is barely five years old, yet it has become the umbrella under which a great deal of space science is conducted. To get an idea of how much is encompassed by this branch of science, visit the Astrobiology Web (www2.astrobiology.com/astro). In addition to posting the latest research news from the field, the site has an impressive listing of astrobiology-related articles and Web pages; subjects range from the first animals to leave Earth (canine cosmonaut Laika and primate cosmonaut Ham) to terraformation (the engineering of planetary environments)

Life in Extreme Environments, for example, profiles a number of interesting (and tenacious) organisms that could conceivably move between planetary systems on space voyages of a million years or more. I was intrigued by the super-bacterium Deinococcus radiodurans (in the Radiation Tolerance section), discovered in a can of beef that went bad despite sterilizing radiation. It can apparently survive a radiation dose of 1.5 million rads (about 3,000 times the level needed to kill most organisms--from microbes to humans) and has a knack for rapidly repairing its DNA. Another bug, Streptococcus mitis (in the Life at Varied Pressures section), supposedly survived for almost three years on the Moon aboard Surveyor 3 in the late 1960s.

A related and perhaps broader subject is astrochemistry, the study of the chemical reactions that lead to the evolution of life. How do inorganic molecules assemble to start life? And how easily does it happen? See NASA's astrobiology site (astrobiology.arc.nasa .gov/index.cfm) for an overview of current research--from microbial mats to the complex organic molecules that form on comets. In the near future, this site will also have a section called Astrobiology for Kids, which will answer questions about how common life is among the stars and how rare Earthlike planets really are.

Robert Anderson is a freelance science writer based in Los Angeles.